Electric discharge lamp



1941- R. F. REED ,2 0 ELECTRIC DISCHARGE LAMP Filed Feb. 15, 1959 F 5 5ROBERT FT/F550,

INVENTOR; WW

" ATTORNEY.

Patented Dec. 23, 1941 ELECTRIC DISCHARGE LAMP Robert F. Reed, Danvers,Mass, asslgnor to Hygrade Sylvania Corporation, Salem, Mass., acorporation of Massachusetts Application February 15, 1939, Serial No.256,498

6 Claims.

This invention relates to electric discharge devices, and particularlyto such devices employing a thermionic electrode.

An object of the invention is to provide for such a device an electrodewhose lead-in and support wires are arranged'to start an auxiliarydischarge sufiicient to facilitate the starting of the main discharge inthe device.

Another object is to properly proportion the various parts of theelectrode and discharge device and their auxiliary equipment to insurethat such auxiliary discharge occurs.

Still another object is to provide anelectrode mount which is easilyassembled in manufacture.

Other objects and advantages of the invention will be apparent from astudy of the following specification, taken in conjunction with theaccompanying drawing, in which: t

Figure 1 is a profile view, partly in section, of a lamp according tothe invention;

Figure '2 is a view of the electrode of Figure 1, in a planeperpendicular to that of Figure 1;

Figure 3 is a view of the -clamped end of the filament of thatelectrode;

Figure 4 is a view of the electrode arranged in a slightly differentmanner; and

Figure 5 is a view of the electrode of Fig. 4, in a plane perpendicularto that of Fig, 4.

In Figure 1, the tubular glass envelope I is sealed at each end. to areentrant stem 2 through which the lead-in wires 3, 4 pass at the pressHi, to support the coiled wire electrode 5. The envelope has the coating6 of fluorescent material on its inner'surface, and has a filling ofinert gas and mercury vapor, for example. The exhaust tube 1, whichmaybe present on one or both of the stems 2, seals the tube. The lead-inwires project forwardashort distance from the stem, and are bent atpoint 8 into a plane perpendicular to the tube-axis.

Figure 2 shows a plan view of the electrode in that perpendicularpl'anethe lead-in wires 3, 4, project toward each other in opposite butessentially parallel directions to the points 9, Ill,

nected to a source of voltage sufficient to bring the filament to anelectron-emitting temperature. The filament is preferably proportionedso that the voltage drop across it with a current suflicient to bring itto the electron-emitting temperature is slightly greater than theresonance or ionization voltage of the gas or vapor in the tube. Therewill then be sufficient voltage between each end of the filament and thelead-in wire to the opposite end to cause a discharge through the gasbetween said end, say end II, and lead-in wire, say 4. This localdischarge will excite the gas along the main path along the length ofthe glass envelope and permit. the starting of that discharge. Thefilament voltage is preferably applied a few seconds before the mainvoltage, and may be cut off as soon as the main voltage is appliedthefilament then acting as a self-heating electrode.

I prefer that the filament in my mount be supported in what I will calla left-handed direction. On looking down at the filament, as in Figure2, we find that the filament is placed along a diagonal extendingdownward to the left (or upward to the right, which is the same thing).I find that such an arrangement is to be preferred, for manufacturingpurposes, to the arrangement in which the filament extends along theopposite, orright handed diagonal (which,

of course, extends downward to the right).

-e filament 5 is preferably made of tungsten wire, and by properlyproportioning the diameter and length of the wire, the filament can bemade to have a voltage drop greater than the resonance or ionizationvoltage of the gas or vapor in the tube at a current sufficient. toraise the temperature of the filament to an electron-emitting valuesufiicient to operate the discharge.

What I claim is:

1. In an electric gaseous discharge device, a tubular glass envelope, astem sealed to an end of said envelope to close off the same, twolead-in wires sealed through said stem in a direction approximatelyparallel to the axis of the tubular envelope and bent in opposite butparallel direc-. tions into a plane perpendicular to, said axis and at ashort distance above the press of the stem,

a doubly coiled, oxide-coated filament each'bf or its ends is disposednear the lead-in wire to the opposite end. I v

2. In an electric gaseous discharge device, a glass envelope, a stemsealed to an end of said envelope to close of! the same, two lead-inwires sealed through the press or said stem and bent into a planesubstantially perpendicular to the axis of said stem, an oxide-coatedcoiled filament in said plane, each end of said filament being clampedto an end or one of the lead-in wires,

the lead-in wires being disposed so that each end of the filament isnear a portion of the lead-in wire to the other end or the filament.

3. The combination of claim 2, a filling oi ionizable gas within theenvelope, and in which the filament is proportioned to have a voltagedrop greater than the ionizing voltage oi said gas for a currentsufficient to raise the filament to an electron emitting temperature.

4. The combination of claim 2, a filling o1 ionizable gas within theenvelope, and in which the filament is proportioned to have a voltagedrop greater than the ionizing voltage of said gas for a currentsufilcient to raise the filament to an electron emitting temperature,and in which the filament is arranged in a left-handed direction.

5. In an electric gaseous discharge device, a tubular glass envelope, astem sealed to mend of said envelope to close ofl the same, adoublycoiled, oxide-coated tungsten wire filament supported with itsaxis straight and substantially in a plane perpendicular to the axis ofsaid tubular envelope, and two wires extending parallel to said filamentand on opposite sides of said filament and in substantially the sameperpendicular plane as the filament, each or ,said straight wires beingconnected to an end of said filament.

6. The combination of. claim 5, a filling of ionizable gas within saidenvelope, and in which the filament is proportioned to have a voltagedrop greater than the ionization voltage of the gas for a currentsuflicient to raise the filament to an electron emitting temperature, inorder that a local discharge may pass from said filament to said wires.

ROBERT F. REED.

